The present invention relates to devices for marking pipe with lines along which cuts are to be made.
Concrete sewer pipe usually is pre-cast in fixed lengths of straight pipe. If a particular installation requires a T-fitting for a sewer lateral or a junction for a vertical riser of a manhole, a first piece of pre-cast pipe is cut with an opening to accommodate the lateral or riser. Another piece of pipe corresponding to the size of the lateral or riser is placed into the opening. The reinforcing wire mesh, commonly called a cage, within each piece of pipe is exposed and welded together at the opening. Then concrete is used to patch the junction between the two pieces of concrete pipe to form a monolithic structure.
One of the problems encountered in this technique is cutting the hole of the proper size and shape to accommodate the lateral or riser pipe. Although this latter piece of pipe has a round cross-section, a non-circular hole must be cut in the first piece of pipe because of that pipe's curved surface. Because the dimensions of this hole heretofore could not be determined with accuracy, fabricators previously cut a much larger hole than was necessary thereby requiring a significant amount of patching to join the two pieces of pipe.
Similar rough approximation techniques are employed to produce angled sections of pipe and "wye" connections.
Therefore, it is desirable to provide a tool which will accurately mark an eclipse of the proper size to accommodate the lateral or riser piece of pipe.